1. Field of the Invention
This invention relates to filled condensation polymer composites and to additives added to the filler for maintaining or enhancing the mechanical properties of the filled condensation polymer composite, including improved hydrolytic stability. More particularly, the invention relates to organosilicon/oxirane additives for maintaining or enhancing these mechanical properties. These organosilicon/oxirane additives being stable at room temperature.
2. Description of the Prior Art
The incorporation of epoxy resins into mineral filled thermoplastic polyester composites has been reported to result in improvements in the as molded mechanical properties. See U.S. Pat. Nos. 3,547,872; 3,547,873; 3,886,104 and 4,034,013. The specific use of epoxy resins in polycarbonates and polyestercarbonates are reported in Netherland patents Nos. 82028930-K-10 and 8202931-K-10. However, the hydrolytic stability of these epoxy resin containing composites is commercially unacceptable.
Japanese Kokai No. 76-30254 (Mar. 15, 1976) teaches the use of an epoxy resin in combination with an aminosilane, such as gamma-aminopropyltriethoxysilane, as a pretreatment for inorganic fillers. This Japanese reference is specific in that 0.02 to 5 weight percent of the aminosilane and 0.1 to 10 weight percent of the epoxy resin, relative to the inorganic filler, must be employed. It is taught in the Japanese reference that to employ more or less than these amounts would adversely affect the thermoplastic polyester composition. Although this approach can overcome the problems associated with hydrolytic stability, the commercial practicality of such a treatment is severely limited by the poor stability of a one-component epoxy resin/aminosilane combination. Indeed, the Japanese reference fails to identify its use as a one-component system even though such systems are preferred commercially.
Thus, there exists the need for an additive which is stable at room temperature and which in filled condensation polymer composites will improve and maintain the mechanical properties of the filled condensation polymer composite. In particular, the composite should exhibit hydrolytic stability.